Sennheiser CXC 700

Selling for more than twice the price of the other NC-IEMS here, and offering far more sophisticated features, the CXC 700 seems like a Ferrari cruising with Corvettes. It features three noise-cancellation modes, tuned for specific situations. One is for subways, short flights, and buses (tuned for best reduction at 100 to 400 Hz); one is for long flights and air-conditioned rooms (400 Hz to 3 kHz); and one is for crowded places like airports and train stations (100 Hz to 3 kHz).

On top of those three modes, the CXC 700 offers the ability to custom-tune the noise-cancelling function to each of your ears — just put the ’phones in your ears and press a couple of buttons. Unlike the other models, the CXC 700 includes a volume control, which is not necessary (your phone or MP3 player has one), but it is handy. And there’s a talk-through key that lets you hear outside sounds without removing the headphones.

Despite its more impressive features list and high price, the CXC 700 didn’t seduce the panelists. Lauren thought bass notes were undefined, sounding more like indistinct thudding than actual pitches, and also found that the output was insufficient when she connected the CXC 700 to her iPhone. Geoff found the sound nasal; he suspected there was a big boost around 3 kHz.

The extra time I got to spend with the CXC 700 lowered my opinion instead of raising it. I needed the biggest tips to get good bass, but even with a good, comfy fit, the bass had the same undefined, bloated sound Lauren complained about. To me, the highs sounded excessively crisp. The upper midrange seemed unnaturally boosted, emphasizing voices but making them sound distorted and rough at the same time. I tried different tips and fussed with the positioning of the earpieces in my ears, but no matter what I did I couldn’t get pleasing sound from the CXC 700. The sound reminded me of some rapper-endorsed headphones, and that’s no compliment.

Paralleling Lauren’s experience with her iPhone, I found the CXC 700 too insensitive even when running full up to attain sufficient volume from my Motorola Droid Pro — especially when I was on the plane, where it didn’t play loud enough for me to hear the music clearly.

Speaking of the plane, I did notice a difference in the various noise cancellation modes. For example, I noticed that NC mode 2 worked as advertised on the 757 I flew from Houston to Denver, delivering the most pronounced reduction in noise. Furthermore, adjusting the noise cancelling for my ears improved the effect even more. However, I can’t say the overall improvement was any greater than what I heard from the simpler Audio-Technica and Phiaton headphones — if even as good. Measurements did indicate, though, that the various NC modes work as they’re supposed to.

The CXC 700’s frequency response measurement shows a pronounced bass boost centered at 40 Hz, which is almost certainly the reason for the panelists’ complaints about the bass fidelity. There are also mild peaks at 2.5 and 6 kHz; again, these are typical for many (if not most) headphones.

Distortion was extremely low, though: just 0.8% THD at 20 Hz at 100 dBA. Impedance is almost perfectly flat and essentially the same with or without NC: 214 ohms with NC active, 213 ohms with NC off. Average sensitivity from 300 Hz to 10 kHz with a 0.179 volts RMS signal is low: 93.0 dB with NC mode 1 on, 92.3 dB with NC off.

It’s obvious that Sennheiser put considerable effort into differentiating the CXC 700 from its competitors, but we’re not convinced that the CXC 700 delivers benefits substantial enough to justify its high price. The low sensitivity made it only marginally usable for us, especially in high-ambient-noise situations. What’s worse, though, is that the sound quality didn’t please any of our panelists. In our opinion, you can do better for less money.